Conveyor Belt Cleaner Scraper Blade with Sensor and Control System Therefor

ABSTRACT

A conveyor belt cleaner scraper blade for cleaning the surface of a conveyor belt and a method of manufacture of the scraper blade. The scraper blade includes a body having a base member adapted to be attached to a cross shaft of a conveyor belt cleaner and a scraping member which extends outwardly from the base member to a scraping tip. The scraper blade includes one or more electrical sensors that are embedded in an insert member. The insert member and the sensors are molded and embedded within the body of the scraper blade. Each of the sensors is adapted to provide an electrical output signal representing a physical condition of the scraper blade sensed by the sensor. A variety of sensor embodiments are described, as well as two embodiments of control and monitoring systems for use in conjunction with the various blade and sensor combinations.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.10/025,091, filed Dec. 19, 2001, now pending, which is acontinuation-in-part of U.S. application Ser. No. 09/454,856, filed Dec.7, 1999, now U.S. Pat. No. 6,374,990, which claims the benefit of U.S.Provisional Application No. 60/111,774, filed Dec. 10, 1998.

BACKGROUND OF THE INVENTION

The present invention is directed to a conveyor belt cleaner scraperblade for scraping adherent material from a conveyor belt, and inparticular to a conveyor belt cleaner scraper blade including one ormore sensors for monitoring the operating conditions of the scraperblade and control system therefore.

Some conveyor mechanisms utilize a moving conveyor belt to transportsand, gravel, coal and other bulk materials, from one location toanother. As the bulk material is discharged from the conveyor belt, aportion of the material often remains adhered to the belt. Conveyor beltcleaners, including one or more scraper blades, are used to scrape theadherent material from the belt and thereby clean the belt. A primaryconveyor belt cleaner may be placed in scraping engagement with theconveyor belt at the head pulley of the conveyor and a secondaryconveyor belt cleaner may be placed in scraping engagement with andbelow the return run of the conveyor belt a short distance behind theprimary conveyor belt cleaner. The scraper blades of a conveyor beltcleaner are removably attached to a rotatable or linearly adjustablecross shaft that extends transversely across the width of the conveyorbelt. A tensioning device is attached to one or both ends of the crossshaft. The tensioning device applies a rotational or linear biasingforce to the cross shaft which in turn moves the scraper blades intoscraping engagement with the conveyor belt with a desired amount offorce. During operation, the scraping edge of each scraper blade wearsdue to its scraping engagement with the rotating conveyor belt. Thetensioner rotates or linearly adjusts the cross shaft and the scraperblades to maintain the scraper blades in biased scraping engagement withthe conveyor belt.

In order to obtain optimum performance from the scraper blades of aconveyor belt cleaner, it is preferable that the scraper blades bebiased into scraping engagement with the conveyor belt with apredetermined amount of force. If the scraper blades are biased againstthe conveyor belt with an excessive amount of force, this will result inexcessive wear to the scraper blades, potential damage to the conveyorbelt, and may cause the tip of the scraper blade to develop anexcessively high temperature due to the friction generated between thescraper blade and the rotating conveyor belt. If the scraper blades arebiased against the conveyor belt with too small of a force, the scraperblades may not effectively clean the conveyor belt. In addition, thescraping tip of the scraper blades may vibrate or chatter against theconveyor belt depending upon the amount of force with which the scraperblades are biased into engagement with the conveyor belt, therebypotentially damaging the scraper blades and/or the belt, and decreasingcleaning efficiency. It is therefore useful to monitor the conditionsand parameters of a scraper blade during operation, such as the scrapingtip temperature, the rate of wear of the scraper blade, and themagnitude of the force with which the scraper blade is biased intoscraping engagement with the conveyor belt, to optimize the performanceof the scraper blade. All of these parameters are subject to changedepending on a number of factors including conveyor belt speed and thetype of material being conveyed.

In addition, a control and monitoring system for the various sensorsincluded in the blade structure would maximize the utility of such asensor array. Even with a variety of sensors present, the user stillmust perform periodic inspections of the installation in order todetermine whether the blades are excessively worn, and to check forproper engagement force between the belt and the scraper blade assembly.Consequently, a need arises for an economically yet durably constructedsystem that is capable of alerting the user to various operatingconditions that may adversely affect the installation, thus avoiding theneed for frequent on-site inspections. Such a control system should alsobe able to automatically adjust the engagement force between the scraperblades and the belt.

SUMMARY OF THE INVENTION

A conveyor belt cleaner scraper blade for cleaning the surface of aconveyor belt. The scraper blade includes a base member adapted to beattached to the cross shaft of a conveyor belt cleaner and a tip memberthat extends outwardly from the base member to a scraping edge which isadapted to engage the conveyor belt. The tip member of the scraper bladeincludes one or more electrical sensors such as temperature sensors,strain detection sensors and/or wear sensors. Each temperature sensorprovides an indication of the temperature of the scraper blade at thelocation of the temperature sensor. The strain detection sensors providean indication of the magnitude of the strain the scraper blade issubjected to during scraping engagement with the conveyor belt. The wearrate sensors provide an indication of the location of the scraping edgewith respect to the base member as the scraper blade wears away due toits scraping engagement with the rotating conveyor belt and as thescraping edge moves closer to the base member. If other conditions needto be monitored other types of sensors may also be utilized. Ultimately,the information which is sensed by the sensors may be transmitted to amicroprocessor that may vary the operating conditions of the conveyorbelt cleaner, including the force applied by a conveyor belt cleanertensioner, or possibly sounding an alarm or other signal when the sensedinformation deviates from preset ranges.

A two-piece scraper blade assembly is disclosed that enhancesremovability of the scraper blade tip in the event that replacementbecomes necessary, as well as providing a secure mounting mechanism toretain the blade tip in position during normal operation. An alternativesensor arrangement is also presented incorporating a unique strainsensor configuration that provides a larger and more informative signaloutput than prior installations.

The control and monitoring system presented herein provides an integralpart of a fully functional, automatically controlled, belt cleaningsystem. The system is capable of monitoring and controlling importantbelt cleaning parameters during conveyor belt operation. A variety ofsensors and actuators are utilized to monitor critical geometry, bladeperformance and conveyed material specifics. The important parameters ofbelt cleaner operation can be adjusted to optimize belt cleanerperformance and blade wear while reducing the damaging effects of thebelt cleaner on the conveyor belt. This optimization is based onprevious belt cleaner research, bulk material properties and behavior,blade composition materials and their behavior, and the interaction ofall of these with the conveyor belt surface.

Control algorithms, with upper and lower bound limits on vibrationlevels, geometry, and pressure (torque) have been coded into a controlsoftware package. These algorithms are based on the relationshipsdescribed above, and are also being continually modified and improvedupon.

A number of unique sensing techniques and structures are utilized tomonitor the important functional relationships, although simpler andmore elegant means are continually being investigated. The systemdescribed herein monitors the presence of material on the conveyor belt;critical geometry (specifically tracking blade length and radialposition-blade angle and other important variables are calculated basedupon these metrics); air line pressure (which is used to control crossshaft torque—i.e., blade pressure at the conveyor belt surface); andblade vibration (multiple blades are monitored). Embedded sensortechniques are employed because of their reliability, durability, andminimal exposure to extreme environmental conditions. A number of newtechnologies are used to obtain viable signals, including electrical andmechanical vibration magnification.

The sensors provided in the cleaning blade are specifically arranged totake advantage of the sensing techniques used, and previous researchconducted, on the behavior of various polyurethane compounds. The tipand base materials are chosen to give acceptable deflection/stresslevels at the sensing element. The interlocking features of the base andtip provide strong electrical signals as well as preventing base/tipseparation during cleaner operation. Replaceable/wearable tips have beenincorporated in the present invention for functionality, simplicity, andto reduce the cost of replacing relatively expensive blade vibrationelements.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of a primary scraper blade according to thepresent invention that is adapted for use in connection with a primaryconveyor belt cleaner.

FIG. 2 is a perspective view of a secondary scraper blade according tothe present invention that is adapted for use in connection with asecondary conveyor belt cleaner.

FIG. 3 is a front elevational view of another embodiment of a primaryconveyor belt cleaner scraper blade according to the present invention.

FIG. 4 is a side elevational view taken along line 4-4 of FIG. 3.

FIG. 5 is a front elevational view of the insert member of the scraperblade of FIG. 3.

FIG. 6 is a side elevational view of the insert member taken along line6-6 of FIG. 5.

FIG. 7 is a top plan view of an insert mold for the insert member ofFIG. 5.

FIG. 8 is a cross sectional view of a body mold for the scraper bladebody of FIG. 3 shown with the insert member positioned therein.

FIG. 9 is a perspective view of an alternative embodiment of a scraperblade in accordance with the present invention.

FIG. 10A illustrates the tip member of the scraper blade of FIG. 9.

FIG. 10B shows the base member of the scraper blade of FIG. 9.

FIG. 11 is a side elevational view depicting interior details of thescraper blade of FIG. 9.

FIG. 12 is a front elevational view depicting interior details of thescraper blade of FIG. 9.

FIG. 13 is a front elevational view of a strain gage sensor andassociated signal magnifying plates suitable for use in the presentinvention.

FIG. 14 is a side elevational view of the strain gage sensor of FIG. 13.

FIG. 15 depicts a single thin beam sensor embedded in a urethane barwith no magnifying plates attached.

FIG. 16 depicts a thin beam sensor embedded in a urethane bar withmagnifying plates attached to each end of the sensor.

FIG. 17 is a perspective view of a scraper blade assembly incorporatingmultiple blades as depicted in FIG. 9.

FIG. 18 is a perspective view depicting interior details of the scraperblade assembly of FIG. 17.

FIG. 19 depicts a monitoring and display system suitable for use instill another embodiment of the present invention.

FIG. 20 illustrates a front panel for a display unit in accordance withthe present invention.

FIG. 21 shows the partial interconnection of system components for themonitor and display system of FIG. 19.

FIG. 22 illustrates another embodiment of a front panel for a displayunit in accordance with the present invention.

FIG. 23A is a front elevational view of a wear panel mold piece suitablefor constructing a wear rate sensor in accordance with one embodiment ofthe present invention.

FIG. 23B is a side elevational view of the wear panel mold piece of FIG.22A.

FIG. 23C is a perspective view of the wear panel mold piece of FIG. 22A.

FIG. 24A is a left side elevational view of a base attachment piece.

FIG. 24B is a front elevational view of the base attachment piece ofFIG. 24A.

FIG. 24C is a right side elevational view of the base attachment pieceof FIG. 24A.

FIG. 24D is a perspective view of the base attachment piece of FIG. 24A.

FIG. 25 is a side elevational view of a cleaner blade mold suitable forforming a scraper blade in accordance with yet another embodiment of thepresent invention.

FIG. 26 is a front elevational view of a scraper blade formed by themold of FIG. 25.

FIG. 27 is a perspective view of system components and identification ofsensors used during operation of a system in accordance with the presentinvention.

FIG. 28A illustrates relative position of system operational componentsat blade wear out.

FIG. 28B shows relative position of system operational components duringinitial system set up.

FIG. 28C illustrates the system operational components at a maintenanceposition.

FIG. 29 shows the configuration variables used in establishing initialconditions for the control system of the present invention.

FIG. 30 illustrates control program operational parameters.

FIG. 31 depicts interconnection of the system sensors with the ADC inputchannels.

FIG. 32 is a flow chart depicting operation of a computer-controlledbelt cleaning system in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The primary conveyor belt cleaner scraper blade 10 of the presentinvention, as shown in FIG. 1, is adapted to be removably attached to across shaft (not shown) of a conveyor belt cleaner for engagement withthe conveyor belt proximate the head pulley such as disclosed in U.S.Pat. No. 4,598,823 of Martin Engineering Company, which is incorporatedherein by reference. One or more scraper blades 10 may be attached tothe cross shaft. A tensioning device, such as disclosed in U.S. Pat. No.5,088,965 of Martin Engineering Company, which is incorporated herein byreference, is attached to the end of the cross shaft and is adapted toprovide selective conjoint movement (either rotational or linear) of thecross shaft and of the scraper blades 10 to move each scraper blade 10into biased scraping engagement with the conveyor belt with, a scrapingforce.

The scraper blade 10 includes a base member 12 that is adapted to beremovably attached to the cross shaft in any of a number of ways knownto one of ordinary skill in the art and a scraping tip 14 that isadapted to engage the conveyor belt. The scraper blade 10 also includesan inner surface 16 that extends from a first bottom edge of the base 12to the tip 14 and an outer surface 18 that extends from a second bottomedge of the base 12 to the tip 14. The inner and outer surfaces 16 and18 extend between a first side wall 20 and a second side wall 22. Theinner and outer surfaces 16 and 18 may each include one or more curvedand/or planar surface portions. The scraper blade 10 includes a wearsection 23 that extends between the inner surface 16 and the outersurface 18 and that extends from the base 12 to the tip 14. The wearsection 23 of the conveyor belt scraper blade 10 is adapted to wearduring use such that the scraping tip 14 as shown in FIG. 1 iseventually located approximately at the bottom end of the wear section23. A wear line 24 is located on the outer surface 18 adjacent thebottom end of the wear section 23. When the scraping tip 14 of the wornscraper blade 10 is located approximately at the wear line 24, such thatthe wear section 23 is substantially worn away, the scraper blade 10should be replaced. The scraper blade 10 is preferably formed from anelastomeric material such as urethane or rubber.

As shown in FIG. 1, the scraper blade 10 includes one or more electricaltemperature sensors 30 that are embedded within the wear section 23 ofthe scraper blade 10, or that are attached to the outer surface 18 ofthe scraper blade 10. One type of temperature sensor that may be used isModel LM 335 from National Semiconductors. The temperature sensors 30are located along the length of the wear section 23 from the scrapingtip 14 to approximately the wear line 24. Each temperature sensor 30 iselectrically connected to a microprocessor 34 which may be located inthe base 12 as illustrated in FIG. 1, or located elsewhere, andelectrically connected to the sensor. One type of microprocessor thatmay be used is Model 68 HC11 microcontroller from Motorola. Themicroprocessor 34 may include a battery to operate the microprocessor 34and data storage means for collecting and storing data. The temperaturesensors 30 are adapted to measure the temperature of the scraper blade10 at locations located along the length of the wear section 23,including the scraping tip 14 of the scraper blade 10. Each temperaturesensor 30 transmits an electrical signal corresponding to thetemperature measured by it to the microprocessor 34. The temperaturesensors 30 may comprise thermocouples.

The scraper blade 10 also includes one or more electrical straindetection sensors 40 such as strain gage sensors. The strain detectionsensors 40 may be embedded within the wear section 23, or attached tothe outer surface 18 of the scraper blade 10. The strain detectionsensors 40 are located along the length of the wear section 23 from thetip 14 of the scraper blade 10 to approximately the wear line 24. As thescraper blade 10 is preferably made of an elastomeric material such asurethane or rubber, the wear section 23 of the scraper blade 10 willresiliently flex between the base 12 and the tip 14 in response to themagnitude of the scraping force with which the tip 14 is pressed againstthe conveyor belt. The strain detection sensors 40 measure the strain ofthe scraper blade 10 due to the flexure of the scraper blade 10, whichcorresponds to the magnitude of the scraping force with which thescraper blade 10 is biased against the conveyor belt. The straindetection sensors 40 thereby provide a measurement that corresponds tothe magnitude of the scraping force with which the scraper blade 10engages the conveyor belt. Each strain detection sensor 40 sends anelectrical signal corresponding to the measured strain and thecorresponding scraping force to the microprocessor 34.

The scraper blade 10 also includes one or more first electrical wearrate sensors 46 and one or more second electrical wear rate sensors 48.The first and second wear rate sensors 46 and 48 are respectivelylocated along the length of the wear section 23 from the tip 14 to thewear line 24 of the scraper blade 10. As shown in FIG. 1, the first wearrate sensors 46 extend along the left edge of the scraper blade 10 andthe second wear rate sensors 48 extend along the right edge of thescraper blade 10. The first wear rate sensors 46 and the second wearrate sensors 48 are electrically connected to the microprocessor 34. Thewear rate sensors 46 and 48 measure the current location of the scrapingtip 14 with respect to a known location on the scraper blade 10, such asthe bottom end of the wear section 23 at the wear line 24, as the end ofthe scraper blade 10 wears during use. Each first and second wear ratesensor 46 and 48 respectively sends an electrical signal to themicroprocessor 34 which signals indicate the current position of thescraping tip 14 with respect to the bottom end of the wear section 23 orthe top of the base member 12. As the outermost wear rate sensors 46 and48 are worn away, a signal is no longer received from these sensorsthereby indicating that the scraping tip 14 has worn past their locationand indicating that the scraping tip 14 is presently located adjacentthe outermost wear rate sensors 46 and 48 that are still sending signalsto the microprocessor 34. Each wear rate sensor 46 and 48 may becombined with a respective temperature sensor 30 as a single combinedsensor. A thermocouple may be used as a combined sensor to indicate bothtemperature and wear rate.

The scraper blade 10 also includes an ambient air temperature sensor 54located in the outer surface 18, near the bottom wall of the base 12 ofthe scraper blade 10, that is adapted to be placed in communication withthe surrounding air. The ambient air temperature sensor 54 measures theambient temperature of the air in the area adjacent to the scraper blade10. The ambient air temperature sensor 54 is electrically connected tothe microprocessor 34 and sends an electrical signal to themicroprocessor 34 that corresponds to the measured ambient airtemperature. The ambient air temperature measured by the ambient airtemperature sensor 54 can be compared to the scraping tip temperaturemeasured by the temperature sensors 30 to determine the temperaturedifferential therebetween, which corresponds to the increase intemperature of the scraping tip 14. The increase in temperature of thescraping tip 14 may be attributable to the friction created between thescraping tip 14 of the scraper blade 10 and the rotating conveyor belt,and/or to the transfer of heat from hot bulk material carried by theconveyor belt to the scraper blade 10.

The microprocessor 34 is electrically connected to an electricaltransmitter member 60, such as an electrical connector member, locatedin the base 12. The electrical transmitter member 60 may be an RS232serial port or other type of port such as an infrared port or a radiosignal port. The electrical transmitter member 60 may be adapted to beattached to a cable that is connected to a computer. The transmittermember 60 transfers data collected by the microprocessor 34 and thesensors to the computer for storage and analysis.

Alternatively, the scraper blade 10 may not include the microprocessor34, and each of the sensors 30, 40, 46, 48 and 54 may be electricallyconnected directly to the electrical transmitter member 60, such thatthe transmitter member 60 will transfer the respective signals generatedby the sensors 30, 40, 46, 48 and 54 to a microprocessor located outsideof the scraper blade 10 or directly to a computer.

Another embodiment of the conveyor belt cleaner scraper blade of thepresent invention is shown in FIG. 2 and is designated with referencenumber 70. The scraper blade 70 is adapted for use in connection with asecondary conveyor belt cleaner, such as described in U.S. Pat. No.4,643,293 of Martin Engineering Company, which is incorporated herein byreference. The scraper blade 70 includes an arm 72 having a first end 74that is adapted to be connected to the cross shaft of the conveyor beltcleaner and a second end 76 that is adapted to be connected to a blade78. The arm 72 and the blade 78 may be respectively formed from anelastomeric material such as urethane or rubber, or may respectively bemade of a metal or ceramic material. The blade 78 includes a base member80 and a wear section 81 having a scraping tip 82. The wear section 81may include a wear resistant insert 83, formed from a metal such astungsten carbide, that is connected to the end of the blade 78 to formthe scraping tip 82.

The wear section 81 of the scraper blade 70 includes one or moretemperature sensors 90 that are located along the length of the wearsection 81 from the scraping tip 82 to a wear line 84 located adjacentto the bottom end of the wear section 81. The temperature sensors 90 areelectrically connected to a microprocessor 94. The microprocessor 94 maybe embedded within the blade 78 or may be adhesively bonded or otherwiseattached to an exterior surface of the blade 78 or may be disposed at aremote location. The microprocessor 94 preferably includes one or morebatteries for powering the microprocessor 94 and data storage means forcollecting and storing data. Each temperature sensor 90 measures thetemperature of the wear section 81 of the scraper blade 70 at itsrespective location, including at the scraping tip 82, and transmits anelectrical signal corresponding thereto to the microprocessor 94.

The wear section 81 of the scraper blade 70 also includes one or morewear rate sensors 98 that are electrically connected to themicroprocessor 94. The wear rate sensors 98 are located along the lengthof the wear section 81 from the scraping tip 82 to approximately thewear line 84. The wear rate sensors 98 indicate or measure the locationof the scraping tip 82 relative to the bottom end of the wear section 81at the wear line 84 as the scraping tip 82 wears down through use. Eachwear rate sensor 98 transmits an electrical signal to the microprocessor94 that is used to indicate the current location of the scraping tip 82.Each temperature sensor 90 may also be combined with a respective wearrate sensor 98 as a combined sensor that indicates both temperature andwear rate. Such a combined sensor may comprise a thermocouple.

The scraper blade 70 may also include one or more strain detectionsensors 100, such as strain gage sensors, for sensing the amount ofstrain the blade 78 is subjected to during operation which correspondsto the scraping force with which the blade 78 engages the conveyor belt.Each strain gage sensor 100 transmits an electrical signal correspondingto the magnitude of the measured strain to the microprocessor 94.

The scraper blade 70 includes an electrical transmitter member 102 thatis electrically connected to the microprocessor 94. The transmittermember 102 is adapted to be electrically connected to a cable andthereby to a computer. Alternatively, the microprocessor 94 may beeliminated from the scraper blade 70 and the sensors 90, 98 and 100 maybe directly connected to the transmitter member 102.

The sensors of the scraper blades 10 and 70 are constructed so as to notwear or groove the conveyor belt. The temperature sensors 30 and 90measure blade tip temperature, which can indicate whether the conveyorbelt is running with or without material, or when the scraper blade isbiased into scraping engagement with the conveyor belt with a larger orsmaller than desired force. The strain detection sensors 40 and 100measure strain and large amplitude vibrations or chatter at the scrapingtip 14 and 82 of the scraper blades 10 and 70 to indicate the number ofhours the scraper blades have been in operation and/or scraper bladechatter. The strain detection sensors 40 and 100 measure and indicateimpact forces applied to the scraper blades 10 and 70 which in turnindicates the condition of the surface of the conveyor belt. The straindetection sensors 40 and 100 also indicate the bending or flexuralstrain in the scraper blades 10 and 70 which corresponds to the forcewith which the scraper blades are biased into engagement with theconveyor belt. The wear sensors 48 and 98 indicate the remaining useablescraping length of the wear sections 23 and 81 of the scraper blades 10and 70 and the rate of wear of the wear sections.

The interval at which the microprocessors 34 and 94 acquire data fromthe sensors may be varied as desired over a practically infinite rangeof intervals. For example, an interval such as sixty seconds forpurposes of research and development could be used and an interval ofapproximately five minutes could be used for service uses. The datastorage capacity of the microprocessors 34 and 94 may also vary over apractically infinite range. For example, a capacity of ninety days ofdata storage capability for research and development purposes may beused, and a data storage capability of one year for service operationsmay be used. The microprocessors may store all of the data collected bythe sensors for review and analysis at a later date or may be connectedto the conveyor drive mechanism and/or tensioning mechanism toautomatically vary the speed of the conveyor belt or the tension appliedto the scraper blades when the sensed data varies from predeterminedranges. Alternatively, the microprocessor may be connected to sound analarm or activate some other signal when certain conditions are sensed.Also the sensors may be connected to display devices such as gages ordigital readout devices to display the conditions being sensed.

FIGS. 3 and 4 show another embodiment of a primary conveyor belt cleanerscraper blade of the present invention identified with the referencenumber 120. The scraper blade 120 includes a body 122 having a basemember 124 and a scraping member 126. The base member 124 includes agenerally T-shaped mounting member 128 at its bottom end which isadapted to be removably attached to the cross shaft of a conveyor beltcleaner. The scraping member 126 extends outwardly from the upper end ofthe base member 124 to a scraping tip 130. The scraping member 126includes the wear section of the scraper blade 120. The scraper blade120 includes an inner surface 132 that extends from a first bottom edgeof the base member 124 to the scraping tip 130 and an outer surface 134that extends from a second bottom edge of the base member 124 to thescraping tip 130. The inner and outer surfaces 132 and 134 of thescraper blade 120 may each include one or more curved and/or planarsurface portions. The inner and outer surfaces 132 and 134 extendlaterally between a first side wall 136 and a second side wall 138.

A generally cylindrical bore 140 extends through the base member 124from the first side wall 136 to the second side wall 138. A projection142 extends outwardly from the first side wall 136 at the base member124. A recess 144 is located in the second side wall 138 at the basemember 124. The bore 140 extends through the projection 142 and recess144. The projection 142 is adapted to be located within and interlockwith a recess in an adjacent scraper blade 120, and the recess 144 isadapted to receive and interlock with a projection from another adjacentscraper blade 120, such that the base members 124 of adjacent scraperblades interlock with one another. The body 122 of the scraper blade 120is preferably formed from an elastomeric material such as urethane orrubber. If desired, the scraping member 126 may include a wear resistantscraping element at the scraping tip 130 which is adapted to engage theconveyor belt. The wear resistant scraping element may be made from awear-resistant material such as tungsten carbide or a ceramic.

The scraper blade 120 includes an insert member 150 as best shown inFIGS. 5 and 6. The insert member 150 includes a generally plate-likemember 152 having a first surface 154 and a second surface 156 which isgenerally uniformly spaced apart from the first surface 154. Theplate-like member 152 includes a generally linear top edge 158, and agenerally linear bottom edge 160 which is spaced apart from andgenerally parallel to the top edge 158. A generally linear side edge 162extends between and is generally perpendicular to the top and bottomedges 158 and 160. A generally linear side edge 164 extends between andis generally perpendicular to the top and bottom edges 158 and 160. Theside edge 164 is spaced apart from and generally parallel to the sideedge 162. The corners between the top edge 158 and the side edges 162and 164 may be curved or rounded. One or more mounting holes 166A-Bextend through the plate-like member 152 from the first surface 154 tothe second surface 156. The mounting holes 166A-B are spaced apart fromone another and are located a generally uniform distance from the topedge 158 of the plate-like member 152. The mounting holes 166A-B arealso each located a generally uniform distance from a side edge 162 and164.

The insert member 150 also includes a mounting member 170 attached tothe bottom edge 160 of the plate-like member 152. The mounting member170 extends generally linearly between a first end 172 and a second end174. The ends 172 and 174 are located outwardly beyond the side edges162 and 164 of the plate-like member 152. As best shown in FIG. 6, themounting member 170 is generally I-shaped in cross section. The mountingmember includes an upper flange 176, a lower flange 178 and web 180which extends generally perpendicularly between the upper and lowerflanges 176 and 178. An elongate generally rectangular channel islocated between the upper and lower flanges 176 and 178 on each side ofthe web 180. The lower flange 178 and the web 180 form an elongategenerally T-shaped mounting member. The insert member 150 is preferablyformed from an elastomeric material such as urethane or rubber.

A mesh sheet 186 is embedded and molded within the plate-like member 152of the insert member 150 adjacent the top edge 158. The mesh sheet 186is located between the surfaces 154 and 156 and extends from a positionadjacent the side edge 162 to a position adjacent the side edge 164. Themesh sheet 186 includes a plurality of apertures. The mesh sheet 186also includes one or more mounting holes 188A-B which extend through themesh sheet 186 and which are adapted to align with respective mountingholes 166A-B in the plate-like member 152. The mesh sheet 186 isgenerally planar and flexible. A preferred mesh sheet 186 is formed fromfiberglass fibers extending longitudinally and transversely in arectangular grid and spaced apart from one another at a center to centerdistance of approximately two millimeters. A preferred mesh sheet 186 iscommonly available dry wall patching material.

The scraper blade 120 includes one or more electrical sensors 196A-Ccoupled to a surface of the mesh sheet 186 and which are thereby coupledto the plate-like member 152 of the insert member 150. The electricalsensors 196A-C are preferably molded and embedded within the plate-likemember 152 between the surfaces 154 and 156. The top ends of the sensors196A-C are preferably located approximately three-quarters of an inchfrom the top edge 158 of the plate-like member 152. Although the insertmember 150 is shown as including three sensors 196A-C, the insert member150 may include only one sensor, two sensors or more than three sensors.The sensors 196A and 196B may be electrical strain detection sensorssuch as strain gage sensors and may be of the uniaxial pattern type ofsensor. One type of strain detection sensor that may be used is PartNumber CEA-06-250UW-120 of Measurements Group, Inc. of Raleigh, N.C. Theelectrical sensor 196C may be an electrical temperature sensor. One typeof temperature sensor that may be used is Part Number ETG-50B ofMeasurements Group, Inc. of Raleigh, N.C. One or more of the sensors maybe a wear rate sensor. Each electrical sensor 196A-C is electricallyconnected to an end of a respective lead wire 198A-C. Each lead wire198A-C is embedded within the plate-like member 152 from the end whichis connected to an electrical sensor 196A-C to a respective exitlocation 200A-C where the lead wires 198A-C extend outwardly from theplate-like member 152 to terminal ends 202 of the lead wires. Theterminal end 202 of each lead wire 198A-C may be electrically connectedto an electrical connector member and thereby to a microprocessor,computer or the like. Each lead wire 198A-C includes at least twoelectrical wires.

As best shown in FIGS. 3 and 4, the insert member 150 is molded andembedded within the body 122 of the scraper blade 120. The plate-likemember 152 is embedded within the scraping member 126 and within thebase member 124 between the inner surface 132 and outer surface 134 ofthe body 122. The plate-like member 152 is generally centrally locatedin the body 122 between and spaced apart from the side walls 136 and 138as shown in FIG. 3. The mounting member 170 of the insert member 150extends across the width of the body 122 from the side wall 136 to theside wall 138. The lower flange 178 and the web 180 of the mountingmember 170 extend into the bore 140 of the body 122. The lead wires198A-C extend from the exit locations 200A-C of the plate-like member150 through the body 122 to an exit location 208. The lead wires 198A-Cextend outwardly from the body 122 from the exit location 208 to therespective terminal ends 202 of the lead wires. The strain detectionsensors 196A-B measure the strain of the scraper blade 120 due to theflexure of the scraper blade 120, which corresponds to the magnitude ofthe scraping force with which the scraper blade 120 is biased againstthe conveyor belt. The strain detection sensors 196A-B each provide ameasurement that corresponds to the magnitude of the scraping force withwhich the scraper blade 120 engages the conveyor belt. Each straindetection sensor 198A-B transmits an electrical signal corresponding tothe measured strain and the corresponding scraping force to amicroprocessor, computer, or other data storage or analysis device. Thetemperature sensor 198C measures the temperature of the scraper blade120 and transmits an electrical signal corresponding to the measuredtemperature to a microprocessor, computer or other data storage oranalysis device. The electrical sensors 196A-C operate in the samemanner as the electrical sensors 30, 40, 46, 48 and 54. The lead wires198A-C may comprise computer communication wire as commonly used inconnection with hard drives and CD-ROM drives in computers, with all buttwo strands of the lead wire removed.

The scraper blade 120 is made by cutting the mesh sheet 186 to a widthof approximately two inches and a length of approximately four inches.The mesh sheet 186 is then placed over a positioning guide (not shown)including indicia which provide the location of each of the electricalsensors 196A-C and of the mounting holes 188A-B. The positioning guidemay comprise a sheet of paper with locating indicia marked thereon. Theelectrical sensors 196A-C are then placed on the surface of the meshsheet 186 in their respective locations as indicated by the locatingindicia on the positioning guide. The electrical sensors 196A-C are thencoupled to the mesh sheet 186 by adhesive tape or other types ofadhesive. The lead wires 198A-C are electrically connected to respectiveelectrical sensors 196A-C by soldering or the like. The mounting holes188A-B are then made in the mesh sheet 186 with a hole punch inlocations as indicated by the locating indicia on the positioning guide.Each end of the mesh sheet 186 is then trimmed such that the mesh sheet186 has an overall length of approximately three inches.

The mesh sheet 186 and the electrical sensors 196A-C are then placed inan insert mold 220 as shown in FIG. 7. The insert mold 220 includes arecess 222 adapted to form the plate-like member 152 of the insertmember 150 and a recess 224 adapted to form the mounting member 170 ofthe insert member 150. The insert mold 220 includes generallycylindrical posts 226A-B located in the recess 222 which extendoutwardly from the mold surface. The posts 226A-B are adapted to beinserted through the mounting holes 188A-B of the mesh sheet 186 toproperly position the mesh sheet 186 and the electrical sensors 196A-Cwithin the recess 222. The mesh sheet 186 is a positioning member forpositioning the sensors 196A-C within the insert member 150 andultimately within the body 120 in a desired location. The insert mold220 also includes apertures 228A-C which are located at positionscorresponding to the exit locations 200A-C of the insert member 150. Theterminal ends 202 of the lead wires 198A-C are inserted through theapertures 228A-C such that the terminal ends 202 are located outside ofthe insert mold 220. The mold 220 is closed and molten elastomericmaterial such as urethane or rubber is poured or injected into therecesses 220 and 224 through a passageway 230 in the mold 220. Themolten elastomeric material flows through the apertures in the meshsheet 186 and adheres to the electrical sensors 196A-C. The elastomericmaterial is then allowed to cool and solidify. The mesh sheet 186 andelectrical sensors 196A-C are thereby molded and embedded within theplate-like member 152 of the insert member 150. The insert member 150 isthen removed from the insert mold 220.

The insert member 150 is next inserted into a scraper blade body mold234 as shown in FIG. 8. The body mold 234 includes a recess 236. Thebody mold 234 also includes a generally cylindrical shaft 238 locatedwithin the recess 236 which is adapted to form the bore 140 in the body122 of the scraper blade 120. The shaft 238 includes an elongategenerally T-shaped slot 240. The T-shaped slot 240 is adapted toslidably receive the lower flange 178 and web 180 of the mounting member170 of the insert member 150. The mounting member 170 thereby slidablyand removably mounts the base or bottom end of the insert member 150 tothe shaft 238 in a desired position within the recess 236. The frontwall of the body mold 32 includes an aperture or slot 242 through whichthe terminal ends 202 of the lead wires 198A-C are inserted such thatthe terminal ends 202 are located outside of the recess 236.

The body mold 234 includes an adjustment member 244 such as a threadedbolt. The adjustment member 244 is threadably attached to the body mold234 such that the tip of the adjustment member 244 is located within therecess 236 and the head of the adjustment member 244 is located outsideof the body mold 234. The adjustment member 244 is selectively rotatedto insert or retract the tip of the adjustment member 244 within therecess 236. The tip of the adjustment member 244 engages the plate-likemember 152 of the insert member 150 and pivots or bends the plate-likemember 150 with respect to the mounting member 170 to thereby locate theplate-like member 152 in a desired location within the recess 236 of thebody mold 234. The insert member 150 is a positioning member forpositioning the sensors 196A-C within the body 122 of the scraper blade120 in a desired location. The body mold 234 is closed and moltenelastomeric material such as urethane or rubber is then poured orinjected into the recess 236 of the body mold 234 to mold the body 122.The molten elastomeric material melts the outer surfaces of theelastomeric material of the plate-like member 152 and of the mountingmember 170 of the insert member 150 that come into contact with themolten elastomeric material. The elastomeric material is allowed to cooland solidify. The insert member 150 thereby becomes integrally attachedto the body 122. The elastomeric material that forms the body 122 ispreferably the same type of urethane or the same type of rubber that isused to form the insert member 150 so that the scraper blade 120 willhave uniform mechanical properties. The adjustment member 244 is thenretracted from the recess 236. The cast scraper blade 120 is thenremoved from the body mold 234.

When the scraping tip 130 of the scraper blade 120 is in scrapingengagement with a moving conveyor belt, the outer end of the scrapingmember 126 will wear away such that the location of the scraping tip 130will move toward the base member 124. When the outer end of the scrapingmember 126 wears to the position of the sensors 196A-C, the sensors196A-C will become worn and will eventually stop functioning. The wornscraper blade 120 may be replaced at this time with a new scraper blade.However, if desired, the worn scraper blade 120 can continue to be usedfor cleaning a conveyor belt as the scraping member 126 can be wornbeyond the sensors 196A-C. The sensors 196A-C are designed such thatthey will not damage the conveyor belt if the sensors engage the movingbelt.

FIG. 9 is a perspective view of an alternative embodiment of a scraperblade, generally depicted by the numeral 900, that shows a tip member901 and a base member 902 in their joined operational configuration.Both the tip 901 and base 902 are preferably formed from a urethanecompound, as set forth above in conjunction with the discussion of theprevious embodiment, but a number of elastomeric materials of sufficientdurability and hardness could also be used. FIGS. 10A and 10B illustratethe tip and base portions, respectively, separated from one another. Asshown in FIG. 10A the tip 901 includes a body having a planar bottomwall 910, an inner surface 912 that extends from a first edge of thebottom wall 910 to a scraping tip or edge 914, and an outer surface 916that extends from a second edge of the bottom wall 910 to the scrapingedge 914. The inner and outer surfaces extend laterally between a planarfirst side wall 918 and a planar second side wall 920. The tip 901includes a pair of spaced apart projecting members (or tabs) 1001 thatextend outwardly from and generally perpendicular to the bottom wall910. A face of each projecting member 1001 includes alternate elongateribs 924 and grooves 926 formed along the length of the projectingmember.

The base member 902 includes a body 930 having a generally planar topwall 932 and a pair of spaced apart generally planar side walls 934. Thebottom wall 910 of the tip 901 is adapted to engage the top wall 932 ofthe base member 902. The body 930 includes a pair of spaced apartcavities 1002 with each cavity 1002 having an opening formed in the topwall 932. An internal face of each cavity 1002 includes alternateelongate ribs 1024 and grooves 1026 formed along the length of thecavity. The projecting members 1001 are adapted to be matingly insertedinto a respective cavity 1002 such that each rib 924 of a projectingmember 1001 is located within a respective groove 1026 of a cavity 1002and such that each rib 1024 of a cavity 1002 is located within arespective groove 926 of a projecting member 1001. These ribs andgrooves engage and interlock with one another when the tip and base areassembled to help hold the two portions snugly together. The projectingmembers 1001 and cavities 1002 form a mounting mechanism for mountingthe tip member 901 to the base member 902.

The base member 902 also includes a projection 1003 that extendsoutwardly from and generally perpendicular to the top wall 932 of thebody 930. The projection 1003 encapsulates a portion of a strain gageassembly molded in place within the base member. This strain gageassembly is discussed in more detail subsequently. The strain gageprojection 1003 is adapted to slide into a mating cavity 1012, shown inFIG. 11, in the tip 901. The cavity 1012 includes an opening 1014 in thebottom wall 910 of the tip 901 between the projecting members 1001.

Other physical features of the blade 900 that are readily visible inFIGS. 9, 10A, and 10B include a mounting bore 903 in the base 902 thatis intended to accommodate a mounting mechanism, such as a cross shaft,for the blade 900. In typical installations, as suggested previously,multiple blades are mounted side-by-side to span even a wide conveyorbelt, and the mounting mechanism generally includes some type ofadjustable tensioner to vary the scraping engagement force between beltand blade. This tensioning device is discussed in more detail below.

Also illustrated in FIGS. 9 through 10B is one embodiment of a lockingmechanism designed to removably secure the tip 901 and base 902together. It should be noted that each of the projecting members 1001that extends from the bottom wall of the tip portion 901 has atransverse groove 1004 along one face. When the tip 901 and base 902 areengaged, a locking rod 904 is inserted into a lock bore 1006 thatextends through the base 902 between its opposing side walls 934. Thislocking rod 904 preferably provides a camming action, so that aprojecting lobe 906 on the locking rod 904 as shown in FIG. 11 can berotated into engagement with the transverse grooves 1004 such that theprojecting members 1001 can not be removed from the cavities 1002, orcan be rotated out of engagement with the grooves 1004 such that theprojecting members 1001 can be removed from the cavities 1002. It isbelieved that rotating the locking rod 904 in and out of engagement ismuch easier than attempting to longitudinally withdraw the locking rod904 altogether from the bore 1006, particularly when the locking rod isused to hold multiple adjacent blade and base sections together. Anactuator mechanism such as a lever or knob is contemplated for one orboth ends of the locking rod 904, in order to make it easier for anoperator to rotate the rod 904 as required. It is also contemplated thata securing mechanism may be associated with the lever or knob, althoughthese details are not illustrated in the drawing figures.

There is also an additional bore 1005 provided in the base portion 902that extends through the base 902 between its opposing side walls. Thisparticular bore 1005 is designed to accommodate the wiring that wouldnormally extend from the sensors disposed on the tip portion 901, andfrom the strain gage assembly that is encapsulated in the base 902. Noneof the wiring is visible in FIGS. 9 through 10B, although these detailsare dealt with subsequently.

It is conceivable that one may connectorize the sensor wiring for easeof assembly/disassembly. Specifically, electrical contacts 1006 may beintegrally formed as a part of the alignment and engagement grooves andribs that appear on both of the projecting members 1001 of the tip 901and in the mating cavities 1002 of the base 902. Such contacts may bedisposed along these mating surfaces using known electroplating ordeposition techniques, then the wires extending from the embedded sensorunits may be attached to these electrical connections as a post-moldingoperation. Of course, it is also possible simply to collect the sensorwires into a cable bundle as discussed above, and to use electricalconnectors in attaching the sensor leads to electrical signaldistribution cables disposed along the conveyor belt cleaning assembly.

Interior views of this embodiment of the scraper blade assembly 900 areshown in FIGS. 11 and 12, featuring considerable interior sensor detail.One should note that the camming nature of the locking bar 904 isparticularly evident in the side view of FIG. 11. The cam lobe 906 ofthe locking bar 904 is adapted to rotate out of the locking grooves 1004and into a recess provided inside the base 902. Of particular interestin the views provided in FIGS. 11 and 12 are the sensors, notably theblade wear sensor 1204, temperature sensors 1201-1203, and the straingage 1210 of the strain gage assembly. The temperature sensors 1201-1203are entirely conventional in design, and are simply embedded in the tip901 by mold-in-place. The temperature sensors 1201-1203 are typicallyaligned vertically as shown in order to monitor temperature along thetip member. Three temperature sensors, spaced evenly, are preferablyused so that temperatures can be extrapolated throughout the remainderof the blade.

The wear sensor 1204 uses a unique geometric design. As is evident froman inspection of FIG. 12, the wear sensor 1204 is preferably a series ofconcentric conductive loops. Each of the loops features one electricalconnection that is common to all of the loops, and one connection thatis unique to a particular loop. For this reason, a wear sensor with fiveconcentric loops requires six electrical connections to the electricalconductors within the geometry. The wear sensor 1204 may include one ormore loops. A wear sensor 1204 including a single loop will indicatewhen a scraper blade is worn to a selected extent, such as completelyworn such that replacement is required.

In one implementation, the concentric loop conductor pattern may bedeposited, such as by conductive ink printing, electroplating, or otherknown process, between two non-conductive layers, such as an acetatematerial. This is the construction technique used in conventional “flex”circuits, such as might be found in modern electronic equipment. As theblade tip 901 wears, the conductive loops are worn away one-by-one, fromthe outermost loop to the innermost loop thus progressively eliminatingconductive paths. One can then “bracket” the remaining tip length inthis quantized fashion by knowing which loops are missing and whichstill remain.

FIG. 12 also depicts the tip member 901 as including an ID(identification) tag 1206. In the preferred form of the invention, an RF(radio frequency) tag system is used, in which a small transmitter sendsa unique digital ID stream to a receiver. The ID tag 1206 uniquelyidentifies the blade tip 901 to ensure, among other things, that theblade tip 901 is the appropriate blade for the cleaning application. Inthe preferred form of the invention, the ID tag 1206 is a CTTC4S activeRFID tag manufactured by CopyTag Limited of Harlow, Essex, U.K. Ofcourse, other RFID tag systems having similar specifications may also besuitable for use with the present invention. Operation of a conveyorbelt scraper blade control system may be disabled if the appropriateblade is not detected.

FIG. 12 further illustrates a radio transmitter 1207 intended fortelemetry transmission. Sensor data from the tip sensors (temperatureand wear rate, at least) may be transmitted by wireless means toeliminate the need to string wires from tip 901 to base 902, and fromeach base member to an appropriate data input module disposed near thescraping blade assembly.

As shown in FIGS. 11 and 12 the base member 902 includes a strainsensor. The strain sensor may be implemented using available devices,although one embodiment features a strain gage assembly including astrain gage sensor 1210 attached to a set of amplifier or magnifyingplates 1205. In the embodiment illustrated, one of the magnifying plates1205 is firmly embedded in the body 930 of the base 902, while the otherplate 1205 is encapsulated within the projection 1003 so that it extendsoutwardly from the body 930 of base 902 and into the cavity 1012 in thetip 901 (as discussed above). FIGS. 13 and 14 illustrate the strain gageassembly including strain gage sensor 1210 and the signal magnifyingplates 1205, as well as showing how the sensor cabling 1208 is dressedalong the plates 1205. As shown, the strain gage 1210 is secured to themagnifying plates 1205 by screws 1701 and nuts 1702. It is intended thatthe strain gage wires 1208 be dressed through opening 1005 in the base902, then passed through the openings 1005 in adjacent bases until allof the sensor wires are connected to an input module for the controlsystem. Of course, as noted above, it is also possible that strain gagedata could be transmitted wirelessly as well, such as over an RF oroptical channel.

The strain gage 1210 itself functions on the principle that when itundergoes strain, its electrical resistance changes. And if therelationship between the relative change in resistance (ΔR/R) and thestrain (ΔL/L, which is defined as the gage factor) is known, then thestrain can be determined. All that is necessary therefore is to measureΔR/R. But this is more easily said than done because the values of ΔRare very small (and ΔR/R, even smaller). In implementing the strain gagesensor assembly 1210, four strain gages are put into a Wheatstone bridgeconfiguration (full bridge with four sensors). This circuit provides alinear relationship among the input voltage, change in resistancevalues, and output voltage. The output voltage is still small and isconsequently run through an amplifying circuit to obtain higher voltagereadings.

The purpose of the magnifying plates 1205 is two-fold. First, the plates1205 provide an insertion method into the mold. More importantly though,the plates 1205 increase the “area of effect” of the strain gage 1210.The “magnifying” effect of the plates is evident if two cases areconsidered. The first case, shown in FIG. 15, is a single thin beamsensor embedded in a urethane bar with no plates attached. The secondcase shown in FIG. 16 is the same beam with an embedded sensor, thistime with plates 1205 attached to the ends of the sensor 1210 (a plateis bolted onto each end of the sensor beam).

The plates 1205 greatly extend the measurement range. The output signalis proportional to the beam deflection (or strain) by a relationship ofthe form:

$\begin{matrix}{{signal} \propto {\int_{A}^{B}{\Delta \ {L}}}} & {or} & {\int_{A}^{B}{ɛ\ {L}}} & {{for}\mspace{14mu} {{case}(1)}} \\{{signal} \propto {\int_{A^{\prime}}^{B^{\prime}}{\Delta \ {L}}}} & {or} & {\int_{A^{\prime}}^{B^{\prime}}{ɛ\ {L}}} & {{for}\mspace{14mu} {{case}(2)}}\end{matrix}$

As is evident, the signal produced by the sensor/plate arrangement inFIG. 16 will be much greater than the sensor alone as in FIG. 15 (due tothe extended length of the plates).

Another amplification effect is related to the width of the plates 1205.The proportionality relationships above would need to be multiplied byelement width to get the total strain/deflection effect. Because theplates are much wider than the sensor itself, this further amplifies theeffect of the blade deflection on the signal.

The width and thickness of the magnifying plates 1205 were chosen tofulfill two purposes. One is the amplification factor described above.Second, the plates cannot be too wide or too thick. The thickness andwidth of the plates should be chosen to maximize the amplification whilenot affecting the overall performance of the blade (if the plates aretoo wide or thick the flexural performance of the blade isaffected—which is not desirable). There appears to be no special orunique shape to the magnifying plates. The plates can be rectangular,circular, elliptical, etc. The length, width, and plate thickness arethe important dimensions in this design. A preferred magnifying plate isapproximately two inches long, approximately one and one-quarter incheswide, and approximately 0.050 inches thick.

This arrangement (sensor/plates) gives an excellent signal that isindicative of blade flexure during operation (blade performance). Anadded feature of this construction is that it minimizes the effect oflongitudinal vibration—which is more related to the type of urethaneused to mold the blade than blade performance (vibration transmittedaxially through the blade will not be amplified by the plates, andconsequently will be of much smaller magnitude).

The strain sensor may alternative comprise a mechanical sensor, such asa contact switch, wherein strain is sensed mechanically. The mechanicalcontact switch is embedded within the scraper blade. When sufficientstrain is placed on the blade the contact switch closes and provides asignal indicating that the scraper blade is engaging the conveyor beltwith sufficient force. When the contact switch is open, it provides anindication that there is not enough strain in the scraper blade toprovide the designed engagement force between the scraper blade and theconveyor belt. The contact distance the contact must travel to close thecontact switch can be adjustable, such as by a set screw, whereby thecontact switch strain sensor can be adjusted to close at selectedmagnitudes of strain depending upon the conditions in which the scraperblade will be used.

Other sensing elements were tried. Biaxial elements were used, mountedexternally on the cross shaft, with some success. Triaxial elements weredetermined not to be necessary as little vibration is transmitted on thecross shaft axis. Accelerometers could easily be mounted internally(inside the blade) but they are expensive, especially the highertemperature accelerometers necessary to withstand the embeddingprocedure—urethane reaction temperatures can exceed 250° F.

FIGS. 17 and 18 depict multiple blade units 900 configured side-by-sidealong a cross shaft (mainframe) 1401 having a linear control axis 1406.It can be seen in particular how the tip locking device 904 is insertedthrough all of the adjacent bases 902 in order to secure the blade tips901 in position.

One embodiment of a system for monitoring and status display of aconveyor belt cleaner involves a novel way of employing wear circuitdetection circuitry. In this form of the invention, an indicator box isplaced outside the conveyor chute and is equipped with visual indicatorsand connection points for a programmable logic controller (PLC). In thisembodiment, rather that being limited to the relatively small number ofwear levels obtainable through the flexible wear circuit describedabove, a method has been developed, using looped wires and an adjustablemold, to realize more flexibility in the spacing of the wear detectionlevels (i.e., one can establish better control of the final wire spacingand not be limited to the fixed increments of the flexible circuit wearrate sensor).

A monitor and display unit for such a system is shown in FIG. 19. Thecircuitry itself is installed in a typical control-type enclosure (withNEMA, explosion proof, etc., options available), with a front panelarranged as in FIG. 20. The looped wire configuration wear circuit iscoupled to the indicator unit of FIG. 20. As the cleaner blade wearsout, the wire loops (2601 in FIG. 21) in the blade are broken and aseries of LED's (light emitting diodes) on the front panel are actuated,indicating the wear level of the blade as a percentage. Two largervisual indicators are used so that the wear status of the blades isvisible from a distance. The “blades OK” indicator 2002 and “servicerequired” indicator 2004, are higher intensity LED's. The “servicerequired” indicator is turned ON (and “blades OK” turned OFF) when thewear level reaches 80-100% worn, for example.

In addition, there are four wireable TTL (transistor-transistor logiclevel compatible) outputs that can be connected to existing PLCequipment (as a 4-bit digital signal). These outputs are “output activelow” and can be up to 24 VDC (volts direct current) with up to a 1ampere source or sink capability to drive relays or other transducers inaddition to standard digital signal inputs. FIG. 21 also indicates atension sensor element 2603 (embedded strain gages) disposed proximatethe wire loop wear sensor 2601 that indicates whether the blades arefunctioning properly, a display unit 2602, and a memory unit 2604capable of tracking hours of operation, wear level, station ID, etc. Thetension sensor element 2603 may be implemented in a variety of ways,such as embedded strain gages or load cell-torque elements attachedeither to the cross shaft or externally on the tensioning system, forexample. In other words, there is more than one suitable way to measureapplied force in this application.

Another embodiment of a monitor and display unit 2218 is shown in FIG.22. The wear circuitry has three different sources of power, namely220VAC, 24VDC and a battery, that can be used independently orsimultaneously. In case of an external power failure the circuit willautomatically run on battery power. The battery is constantly charged byeither the 220VAC or 24VDC power supply. When the scraper blades are newall five wear indicator lights 2220A-E, such as LED's, are lit or on,and the upper remote alarm light 2222A will also be on. The lights2220A-E respectively turn off when the scraper blade is twenty percentworn, forty percent worn, sixty percent worn, eight percent worn andone-hundred percent worn. When the blade is eighty percent worn thelight 2220D turns off, the upper remote alarm light 2222A will also turnoff, and a lower remote alarm light 2222B will turn on. When the bladeis one-hundred percent worn the light 2220E will turn off and the remotealarm lights 2222A and B will start flashing. The display unit 2218 alsoincludes a system test button 2226, a DC power on indicator light 2228,an AC power on indicator light 2230, an AC power on button 2232, an ACpower off button 2234, and fuses 2236.

The blade wear sensor 2601 as shown in FIG. 21 is actually implementedas true embedded wires in accordance with this embodiment. Embeddedwires form an eminently suitable and economical implementation for bladewear sensing, provided the wires can be supported properly formold-in-place into the urethane mold. As noted previously, cost of theflexible circuit and limitations in wear circuit geometry can poseproblems in some installations.

One technique for implementation of actual wire loops such as those ofthe blade wear sensor 2601 within a blade structure is the use of amulti-step pouring method to embed the looped wires into the cleanerblades. The first step is to locate the looped wires in a moldedpolyurethane “panel” 2002, as illustrated in FIGS. 23A-C, that is laterinserted into the actual cleaner blade mold. The flat wear panel 2002 isadjustable in length and also allows one to vary the wire spacing. Thus,the panel 2002 can be changed to fit into a variety of different cleanerblades (different profiles, sizes, and with different wearable lengths)without having to make more molds. The flat piece/wear panel 2002 isthen pressed between two steel plates in the shape of the profile of thecleaner blade the wear panel is to be inserted into. This forces thewear panel to take the shape of the cleaner blade profile (if apolyurethane piece is pressed into a shape before it is “cured” it willkeep that shape after it cures).

The wear panel 2002 is adjustable and includes “half moon” curved spacerpieces 2301 that can be placed anywhere along the length of the panel,and the length of the final panel can be varied by putting a plug intothe end of the mold for the panel 2002 (a 4 inch to 14 inch insert piececan be poured), or by cutting the panel 2002 to size after molding. Thepanel 2002 includes a plurality of apertures 2304 that extend along thecentral linear axis of the panel 2002, and flanges 2306 located alongopposing sides of the panel 2002. The bottom end of the panel 2002includes a general T-shaped member 2308. The “half moon” spacer pieces2301 are positioned using locating screws 2310 that extend throughrespective apertures 2304. Each wire of the wear sensor 2601 is loopedaround a respective “halfmoon” spacer piece 2301. These spacer piecesallow one to customize placement and spacing of the wear rate sensorwires (they can be placed as close as 0.7 inch apart with no real limiton the upper spacing). It should be noted that the circuitry used toconvert the wear levels into an output signal is set up to accept eithera 5 level or 10 level wear circuit (or 5 or 10 level looped wire setup).The varying diameter/width of these “half moon” spacer pieces allow thewires to be offset, preventing interference and the possibility of anerroneous signal.

The second piece required for this new wear rate sensor methodology is abase-attachment piece 2201. The function of this piece is to secure thewear panel piece 2002 into the cleaner blade mold for final production.A base attachment piece 2201 for one cleaner blade style is shown inFIGS. 24A-D. The base attachment piece 2201 includes a planar bottomwall 2210, a planar front wall 2212, a planar rear wall 2214 spacedapart and parallel to the front wall 2212, a planar first side wall2216, and a planar second side wall 2218 that is spaced apart andparallel to the first side wall 2216. The upper end of the attachmentpiece includes a generally T-shaped slot 2202 that is located in anupper wall 2204 and that extends between and through the side walls 2216and 2218. The base attachment piece 2201 locates the T-shaped member2308 of the wear panel 2002 in slot 2202 and secures the panel 2002 inthe cleaner blade mold for final pouring. The base attachment piece alsoincludes a curved slot 2203. The curved slot 2203 includes a rectangularopening in the front wall 2212 and rear wall 2214, and a curved openingin the second side wall 2218.

The two pieces, wear panel 2002 and base attachment piece 2201, are fittogether by the interference fit slot 2202 as noted, the male T-shapedend 2308 on the wire-locating panel 2002 being slidably inserted intothe female T-shaped slot 2202 on the base-attachment piece 2201. Thesepieces are put together and placed/located in the “final” cleaner blademold 2001 using the base-attachment piece as shown in FIG. 25. Forexample, as shown in FIG. 25 the base-attachment piece 2201 depicted inFIGS. 24A-D fits over a standard metal insert 2208 within the mold 2001with the insert 2208 being located within the curved slot 2203. Thebase-attachment piece 2201 fits into/around the metal insert 2208,placing and securing the wire-locating mold piece 2002 and the wear ratesensor attached thereto into the final scraper blade mold 2001 forpouring. The resulting scraper blade is shown in FIG. 26.

A control system designed for proper operation of a completely automatedconveyor belt cleaner scraper blade installation, as shown in FIG. 27,determines its operational parameters at start-up, performs aself-calibration, and moves the scraper blades into a properly computedengagement attitude and pressure with respect to the belt.

As shown in FIG. 27, one or more scraper blades 900 are mounted on thecross shaft 1401. The scraper blades 900 and cross shaft 1401 areconjointly rotatable about the axis 1406 of the cross shaft 1401. Eachend of the cross shaft 1401 is attached to a rotary actuator 3102 thatprovides selective rotation of the cross shaft 1401 and scraper blades900 about the axis 1406. The rotary actuators 3102 may be pneumaticrotary actuators, such as the PHD Model RLS1 63×270 rotary actuator. Atorque sensor 2709, such as the Parker Pneumatic P3P-R Serieselectro-pneumatic pressure regulator, is coupled in fluid communicationwith the rotary actuators 3102. The torque sensor 2709 includes apressure sensor and a valve that regulates the pressure of the air thatis supplied to the rotary actuators 3102. The torque sensor 2709provides an output signal that is indicative of the pressure of the airsupplied to the rotary actuators 3102. The torsional output force of therotary actuators on the cross shaft 1401 is calculated from the pressureof the air supplied to the rotary actuators 3102. The force with whichthe scraper blades 900 engage the belt is selectively adjusted by thetorque sensor 2709 varying the pressure of the air supplied to therotary actuators 3102. If desired, a torque sensor 2707, such as aTransducer Techniques TRS series flanged reaction torque sensor, may beused to couple one end of the cross shaft 1401 to one of the rotaryactuators 3102. The torque sensor 2707 measures the magnitude of thetorsional force with which the rotary actuators 3102 rotate the scraperblades 900 into scraping engagement with the belt 2701 and provides acorresponding output signal.

Each rotary actuator 3102 is attached to a first end of a first bracket2720. The second end of the first bracket 2720 is rotatably mounted to astationary support member such as a mounting plate 2722. The second endof the first bracket 2720 is fixedly attached to the first end of asecond bracket 2724. The first bracket 2720, second bracket 2724, rotaryactuators 3102, cross shaft 1401 and scraper blades 900 are adaptedconjointly rotate about a linear axis 2726. A linear actuator 2801having a cylinder 2732 and an extendable and retractable ram 2734 ispivotally attached at one end to the second end of the second bracket2724 for pivotal movement about an axis 2736, and is pivotally attachedat a second end to a stationary support member such as a mountingbracket 2738. The linear actuator is preferably pneumatically operated,but could be hydraulically operated if desired. Selectiveextension/retraction of the ram 2734 conjointly rotates the brackets2720 and 2724, rotary actuators 3102, cross shaft 1401 and scraperblades 900 about the axis 2726 to a desired rotational position which isadjusted as the scraper blades 900 wear. An angular displacement sensor2740, such as the Baumer Electric MDRM 18U9501 magnetic encoder, sensesthe rotational position of the brackets 2720, 2724, rotary actuators3102, cross shaft 1401 and scraper blades 900 about the axis 2726. Theradial displacement and the angle of attack of the scraper blades 900 isselectively adjusted by the actuators 3102 and 2801. Each actuator 2720and 2801 may respectively include a position sensor to provide a signalindicative of the position of the actuators 2720 and 2801 from which theposition and cleaning angle of the scraper blade 900 can be computed.The position sensors may be linear or rotary variable resistancesensors.

Operational attitudes for a scraper blade assembly are illustrated inFIGS. 28A-C. FIG. 28B depicts an initial attitude in which the bladeassembly 900 is in proper initial scraping engagement with a conveyorbelt 2701. The head pulley 2702 for the belt 2701 is located near thedischarge end of the conveyor. The head pulley rotates about a centrallinear axis 2704. FIG. 28A depicts an attitude in which the blade 900 iscompletely worn and requires replacement. FIG. 28C depicts an attitudein which the blade 900 is positioned for maintenance, such as theremoval of a worn blade 900 and replacement with a new blade.

It is also envisioned that data gathered and stored from eachinstallation may have significant impact on problem tracking at specificinstallations, as well as the establishment of programmed maintenanceschedules that can lead to recommendations to the end user on when toreplace the tips 901 for a particular belt. The control system also hasthe capability to activate both local and remote alarms to notify theuser about relevant conditions.

A noteworthy aspect of the control system of the present invention isthat the sensors and positioning mechanisms described do not directlymeasure the angle of attack that the scraper blade makes with the belt.This information is computed based upon the known position of the radialtensioner 3102 with respect to the belt, combined with the known lengthof the scraper blade tip and base. Of course, depending upon thespecific embodiment used for the wear rate sensor, the length of thescraper blade is only known within a range that is dependent upon thedistance between sensor “tracks” of the blade length sensors. Similarcalculations can be made even if the pneumatic positioning cylinders areeliminated from the installation because of space considerations.

As depicted in FIG. 27, a variety of sensors are available for thecentral controlling processor of this system to evaluate. As mentionedabove, there are both temperature sensors and strain gage sensors withinthe blade. There may be a material detection sensor 2710 located closeto the belt, such as a Baumer Electric Model FHDM 16P5001 photoelectricdiffuse sensor, although non-photoelectric sensors may be used. Thematerial detection sensor 2710 determines whether there is material onthe belt being transported. There may also be a belt speed sensor 2703,such as a Siemens Milltronics Model RBSS (Return Belt Speed Sensor), fordetermining the speed of the belt. There may be a material carry backsensor 2705 for sensing whether and to what extent conveyed materialremains adhered to the belt after passing by the scraper blades 900,such as the ICT Automated Carryback Monitor of ESS Engineering Servicesand Supplies in Corrumbin, Australia. A belt splice detector sensor2704, such as the GO Switch Model 11-12528-A3 sensor, may be providedfor sensing the location of the belt splice as it approaches the scraperblade 900. In addition, there may be a sensor for ambient airtemperature to provide baseline data for the other temperature sensors.

A great deal of information is derived from the blade-mountedtemperature sensors and strain gage sensors to enable an accuratedetermination of whether the blade is engaged against the belt with theproper force to provide proper cleaning. One may also be able to predictwhen the belt coupling (or splice) is approaching the blade (based uponstrain gage information and computation using belt speed information),even without a specific splice detection sensor 2704. It is conceivablethat blade engagement force may need to be reduced prior to the beltcoupling passing under the blade. The type of action to be taken inresponse to belt coupling approach may depend upon the style of belttensioner and positioning mechanism used in a particular installation.At the very least, sensor data enables a determination of when the bladeshould be replaced, as well as providing an indication that bladeposition and engagement tension or force are correct with respect to thebelt in use and the material conveyed.

It is also noteworthy that, since a microprocessor is used in the datagathering and computation platform, a database of sensor information canbe maintained offline. Such a database could be maintained locally ortransmitted to a remote location (such as via the Internet) for storage.It may be possible to analyze accumulated data for additionalinformation about a particular customer location.

The preferred embodiment of the control system includes a microprocessorfor receiving and analyzing the signals and information representedthereby from the sensors placed at various positions within the system.However, the conveyor belt cleaner system can be controlled without theuse of a microprocessor, such as by use of analog logic circuitsincluding, for example, on-off switches, relays and indicator lights.Similarly, digital logic, short of a microprocessor, could also be usedto receive and interpret sensor signals.

FIG. 29 shows the configuration values used in establishing initialconditions for the control system of the present invention prior toactual operation. These parameters are identified in FIG. 29 in astylized representation of the blade and belt configuration shown inFIGS. 28A-C. FIG. 30 illustrates the control program operationalparameters.

The system software automatically calibrates the system and establishesoperating parameters, then monitors system operation in real time,making any necessary adjustments of the cleaning blade assembliesrequired to ensure maximum cleaning effectiveness. Measured values fromthe system's array of sensors are compared to optimum computed limits,and the system makes adjustments based upon specified rules to try andcorrect any problem that may have arisen. Indicators associated with thecontrol system advise the end user of any required action.

The system software is stored as a program in a memory device. Aprocessor operative with the memory defines a set of initial conditionsthat establish the initial radial displacement of the conveyor beltcleaner scraper blade with respect to the conveyor belt. The processormonitors output signals from the sensors, computes the angle of attackof the scraper blade with respect to the conveyor belt and the forcewith which the scraper blade engages the belt, determines current systemperformance based upon measured sensor signals, and controls theactuators to adjust scraper blade angle of attack and blade engagementforce to optimize current system performance. The software alsorecognizes what sensors and actuators are present or missing. Thus,different program routines are disabled depending upon the configurationpresent. For instance, if there is no material sensor present, the“check for material” routine of the programming would be disabled.

In its preferred form, sensor data is input to a microprocessor-basedsystem that includes a 16 channel, 16-bit analog-to-digital converter(ADC), two serial communication ports, four 8-bit digital-to-analogconverters (DACs), two digital input ports, and a digital output port.FIG. 31 illustrates interconnection of the system sensors with the ADCinput channels. ADC data is collected for seven channels with 4,000 datapoints sampled for each channel. This is a total of 28,000 data points.Using two bytes for each sample point, a buffer size of 56 K bytes isrequired. During the calibration portion of system initialization,measurements are taken as required while the conveyor belt itself is notrunning. Data is acquired when the conveyor belt is running, andrecalibration may be done when the belt is stationary. If the totalcalibration routine could not be completed, the system uses the valuesobtained from its last complete calibration.

A flow chart of program operation is shown in FIG. 32. The OperatingProgram block 3201 acquires each data snapshot, sampling during a givenduration and using a pre-programmed sampling interval. The OperatingProgram block 3201 is also responsible for time stamping the acquireddata block and writing the data block to memory.

After data acquisition, there is a set of Global Checks that areperformed. These Global Checks include:

(1) Current blade length. This is determined by the signal from theblade wear sensors. Based upon the current blade length value, theOperating Program 3201 updates the position/pressure algorithms that useblade length from computation, then the Operating Program 3201 may electto reset the current system pressure/position values to reposition theblade in accordance with the current blade length value.

(2) Material present on carrying side of belt. This information isderived from the output signal of the material present sensor. Systemstatus may be updated dependent upon the current reading, changing fromIdle to Operational, for example.

(3) Belt motion/speed. This parameter is derived from the measuredoutput of the belt speed sensor. In response to the speed value,calibration parameters may need an update, the system may requirere-calibration, and the data sampling speed may need to be updated. Atvery low belt speeds, for example, the sampling speed may be reduced.

(4) Belt splice detection. The approach of the belt splice is generallyindicated by a dedicated sensor, although it is also possible to predictthis event by noting a characteristic “signature” appearing within thestrain gage data and computing the splice reappearance based upon knownbelt speed. As the splice passes the blade, it may be necessary toreduce blade engagement pressure, then restore it after the splicepasses. This action can help reduce blade wear.

There is also a series of Dynamic-Waveform Checks specified within theOperating Program block 3201. These are as follows:

(5) Measured radial position. Since precise angle of attack of thescraper blade with respect to the belt cannot be measured, thisparameter must be computed based upon knowledge of the position of thetensioner (the radial position) acquired through angular and lineardisplacement sensors disposed on the cross shaft. As noted previously,of course, the exact configuration of the cross shaft may vary frominstallation to installation (a linear positioning capability may not beneeded, for example). This information is known because it is part ofthe pre-programmed system parameters. Necessary spatial coefficients,including blade angle of attack, are computed from the measured radialposition and the measured blade length. One will recognize that theseparameters may change during the life of the blade.

(6) Measured system pressure/tension applied. The cross shaft torqueprovides a direct indication of the amount of engagement force betweenthe blade and the belt, and this torque value can be measured directlyfrom the torque sensor. Based upon system pressure and empiricalinformation, performance of the system can be predicted in terms ofblade deflection as indicated by the strain gage sensor output values.

(7) Measured blade deflection. Blade deflection is measured everysampling interval by collecting strain gage output values. These valuesare compared to the values predicted based upon the known tensionapplied between the blade and the belt. If the measured values differsignificantly from the values predicted by the model, then systemadjustment may be required.

(8) Cleaning performance. An indirect indication of cleaning performanceis provided either directly by a carry back sensor positioned on theconveyor belt underside, or by analysis of the strain gage sensoroutputs. A blade deflection profile that matches up well with empiricaldata for a given tension value indicates proper performance. If thestrain gage values do not match up well with the model, then adjustmentis required. Of course, carry back sensor readings and strain gageoutput profile can be combined to analyze cleaning performance of thesystem.

Other necessary program segments are called from the Operating Programblock 3201. These include the Input-Programmed System Parameters block3204 that acquires system information necessary to fine-tune thepredicted performance model to a specific installation. The parametersacquired in this program block 3204 are generally programmed manually bythe system installer or user rather than being detected by readingsensor values.

The information collected by this program module 3204 includes thecleaner type, number of scraper blades installed as well as the bladeinstallation location and angle, and the type and number of tensioningelements. As noted, there are applications in which both linear andangular actuators may not be required, and the program needs to knowwhich are present.

The Input-Programmed System Parameters block 3204 also requires that theuser or installer specify any rotary or linear tensioning options. Thesemay include, for example, the specific types of linear and rotaryactuators installed on the system, and the specific sensor types thatindicate linear and rotary position. There may also be site specificsthat impact system operation. These may include the ambient temperaturerange at the site, for example, as well as the type of material beingconveyed. There may also be system options associated with sensing,monitoring, and control, such as type of alarm or action to be takencorresponding to specific blade wear indications.

The Global-Operational Algorithms block 3203 includes the algorithmsthat permit prediction of system performance based upon measured values,as well as computation of desired system settings. For example, one ofthe algorithms computes cleaning pressure based upon linear and angularposition data combined with current blade length measurement. Another ofthe routines included in this block acquires the cleaning blade IDprovided by the RFID tag (or other identification protocol) and verifiesthat the blade ID is appropriate. Certain operational checks can also beenabled or disabled based upon hardware and sensor configuration.

The Self-Calibration/Installation Routine 3202 determines upper andlower system pressure limits. This routine accomplishes this task bycalculating the minimum, midpoint, and maximum radial positions of thebelt cleaner cross shaft (mainframe) system.

The mainframe is then located to its maximum radial position, and threelevels of tension are applied to the system in succession. At eachtension level, the blade strain and system torque are measured andrecorded, and the element correlation coefficients that relate systempressure, blade deflection (strain) and mainframe torque are calculated.This process is repeated both the midpoint and minimum radial positions.The necessary spatial coefficients that determine the empiricalrelationship between the element coefficients and the mainframe positionare then calculated. After these calculations are completed, themainframe is moved to its pre-programmed initial position and defaultpressure is applied.

Various features of the invention have been particularly shown anddescribed in connection with the illustrated embodiments of theinvention, however, it must be understood that these particulararrangements merely illustrate, and that the invention is to be givenits fullest interpretation within the terms of the appended claims.

1-55. (canceled)
 56. A strain gauge sensor assembly for a conveyor beltcleaner scraper blade, said strain gauge sensor assembly including: astrain gauge having a first end and a second end; a first magnifyingmember attached to said first end of said strain gauge; and a secondmagnifying member attached to said second end of said strain gauge. 57.The strain gauge sensor assembly of claim 56 wherein each saidmagnifying member comprises a plate.
 58. A conveyor belt scrapercomprising: a urethane scraper blade; a strain gauge embedded within thescraper blade, the strain gauge having opposite edge portions; first andsecond spaced apart magnifying members embedded within the scraperblade, the first magnifying member being attached to one of the oppositeedge portions of the strain gauge and the second magnifying member beingattached to the other of the opposite edge portions of the strain gaugein a manner such that deflection of the scrapper blade causes the firstmagnifying member to move relative to the second magnifying member andthe strain gauge is able to detect such relative movement.
 59. Aconveyor belt scrapper in accordance with claim 58 wherein the scraperblade comprises a base member portion and a tip member portion that areremovably attached to each other, the tip member portion comprises acavity, and the strain gauge and the first and second magnifying membersare fixed to the base member portion, and one of the first and secondmagnifying members is positioned in the cavity of the tip member portionwhen the base member portion and the tip member portion are attached toeach other.